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A320 OPS with QNH below 950 hPa

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A320 OPS with QNH below 950 hPa

Old 8th Mar 2008, 17:56
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A320 OPS with QNH below 950 hPa

In reference to this thread, I would like to ask whether any operators have procedures in place to operate at a QNH below 950 hPa, as our older ships' FCUs wont go below 950.

We were recently discussing the problem for the discussions sake and couldn't come up with a real work-around as

- STBY Altimeter also goes only to 950
- Vertical Separation might be affected when using 950 iso the actual QNH
- QFE-Ops only helps on an significantly elevated airfield

Who did it already and how? Private Procedures or official ones? What are other types limited to? Any insights appreciated...

Safe flights, MAX
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Old 8th Mar 2008, 18:12
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Better look up your procedures for QNE then
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Old 9th Mar 2008, 01:23
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QFE-Ops only helps on an significantly elevated airfield
QFE Ops would make the problem worse! (Unless you operate to airfields below sea level)
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Old 9th Mar 2008, 09:31
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Be careful!! You might find that if your ac are pin programmed for Qnh and you make a Qfe approach that Mr Honeywell's trusty (E)Gpws will have something to say as the granite approaches.

Cheers,
mcdhu
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Old 9th Mar 2008, 11:03
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QNH = 950 HPa. Take a 270 ft elevation airfield and the QFE = 940 HPa!

Can we get back to basics chaps? Jeez
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Old 10th Mar 2008, 11:41
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212man is right, of course. That should be obvious.

Unless you operate within a very limited area, where all operators can agree to deconflict with each other on an arbitrary (e.g. 950) pressure setting (e.g. it has been done in the North Sea) - then QNE is the only solution. But will / can ATC provide it? That is the question.

And, equally obviously, that only takes care of other traffic. Doesn't help with terrain clearance en route.
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